Permeate Flux Analysis of Direct Contact Membrane Distillation (DCMD) and Sweep Gas Membrane Distillation (SGMD)

직접접촉식과 동반기체식 막증류 공정의 투과수 변화에 따른 비교해석

  • Eum, Su-Hwan (Department of Chemical Engineering, College of Engineering, Kyung Hee University) ;
  • Kim, Albert S. (Department of Chemical Engineering, College of Engineering, Kyung Hee University) ;
  • Lee, Yong-Taek (Department of Chemical Engineering, College of Engineering, Kyung Hee University)
  • 엄수환 (경희대학교 공과대학 화학공학과) ;
  • ;
  • 이용택 (경희대학교 공과대학 화학공학과)
  • Received : 2011.06.21
  • Accepted : 2011.09.21
  • Published : 2011.09.30

Abstract

In this study, we used prepared a cylindrical module consisting 100 hollow fibers of commercialized (hydrophobic) polyethylene membrane of $0.4{\mu}m$ pore size and systematically studied performance of direct contact membrane distillation (DCMD) and sweep gas membrane distillation (SGMD) in terms of variation of permeate flux and salt rejection with respect to temperature drop across the membrane, salt concentrations in feed, and flow rates of cooling water and sweep gas. SGMD was regarded as DCMD with a sweep gas layer between permeate-side membrane surface and cooling water. Sweep gas flow decreases the permeate flux from that of DCMD by providing an additional gas-layer resistance. We compared DCMD and SGMD performance by using mass balance with a fitting parameter (${\omega}$), indicating fraction of permeate flow rate.

본 연구에서는 기공의 크기가 $0.4{\mu}m$의 소수성 막인 폴리에틸렌 100가닥으로 모듈을 제작하여 직접접촉식과 동반기체식 막증류 과정에서 막의 양단의 온도차, 공급수의 염분농도, 그리고 냉각수/동반기체의 유량에 대해서 투과수의 플럭스를 측정하였다. 이론적으로는, 동반기체식 막증류는 직접접촉식 막증류 공정의 막의 투과측 표면과 냉각수 사이에 동반 기체층이 추가된 것으로 간주하였다. 이 동반기체층은 새로운 저항층과과 동반기체의 이동중 상변화된 수증기가 손실되는 것이 투과유속을 30% 정도 감소시키게 된다. 물질수지식을 이용하여, 기존의 식과는 다르게 보정계수(${\omega}$)를 넣어 직접접촉식 막증류와 동반기체식 막증류의 이론값을 실험값과 비교 분석하였다.

Keywords

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